refactor(material-experimental/column-resize): fix strict property initialization errors

Updates the code to be compatible with strict property initialization.

Author: crisbeto

src/material-experimental/column-resize/column-resize.spec.ts

@@ -158,7 +158,7 @@ const MOUSE_START_OFFSET = 1000;
 
 @Directive()
 abstract class BaseTestComponent {
-  @ViewChild('table') table: ElementRef;
+  @ViewChild('table') table!: ElementRef;
 
   abstract columnResize: AbstractMatColumnResize;
 
@@ -279,7 +279,7 @@ abstract class BaseTestComponentRtl extends BaseTestComponent {
   imports: [BidiModule, MatTableModule, MatColumnResizeModule],
 })
 class MatResizeTest extends BaseTestComponent {
-  @ViewChild(MatColumnResize) columnResize: AbstractMatColumnResize;
+  @ViewChild(MatColumnResize) columnResize!: AbstractMatColumnResize;
 }
 
 @Component({
@@ -294,23 +294,23 @@ class MatResizeOnPushTest extends MatResizeTest {}
   imports: [BidiModule, MatTableModule, MatDefaultEnabledColumnResizeModule],
 })
 class MatResizeDefaultTest extends BaseTestComponent {
-  @ViewChild(MatDefaultEnabledColumnResize) columnResize: AbstractMatColumnResize;
+  @ViewChild(MatDefaultEnabledColumnResize) columnResize!: AbstractMatColumnResize;
 }
 
 @Component({
   template: getTableTemplate(true),
   imports: [BidiModule, MatTableModule, MatDefaultEnabledColumnResizeModule],
 })
 class MatResizeDefaultRtlTest extends BaseTestComponentRtl {
-  @ViewChild(MatDefaultEnabledColumnResize) columnResize: AbstractMatColumnResize;
+  @ViewChild(MatDefaultEnabledColumnResize) columnResize!: AbstractMatColumnResize;
 }
 
 @Component({
   template: getFlexTemplate(false),
   imports: [BidiModule, MatTableModule, MatColumnResizeModule],
 })
 class MatResizeFlexTest extends BaseTestComponent {
-  @ViewChild(MatColumnResizeFlex) columnResize: AbstractMatColumnResize;
+  @ViewChild(MatColumnResizeFlex) columnResize!: AbstractMatColumnResize;
 }
 
 @Component({
@@ -319,7 +319,7 @@ class MatResizeFlexTest extends BaseTestComponent {
 })
 class MatResizeDefaultFlexTest extends BaseTestComponent {
   @ViewChild(MatDefaultEnabledColumnResizeFlex)
-  columnResize: AbstractMatColumnResize;
+  columnResize!: AbstractMatColumnResize;
 }
 
 @Component({
@@ -328,7 +328,7 @@ class MatResizeDefaultFlexTest extends BaseTestComponent {
 })
 class MatResizeDefaultFlexRtlTest extends BaseTestComponentRtl {
   @ViewChild(MatDefaultEnabledColumnResizeFlex)
-  columnResize: AbstractMatColumnResize;
+  columnResize!: AbstractMatColumnResize;
 }
 
 interface PeriodicElement {

src/material-experimental/column-resize/overlay-handle.ts

@@ -53,7 +53,7 @@ export class MatColumnResizeOverlayHandle extends ResizeOverlayHandle {
   protected readonly styleScheduler = inject<_CoalescedStyleScheduler>(_COALESCED_STYLE_SCHEDULER);
   protected readonly document = inject(DOCUMENT);
 
-  @ViewChild('top', {static: true}) topElement: ElementRef<HTMLElement>;
+  @ViewChild('top', {static: true}) topElement!: ElementRef<HTMLElement>;
 
   protected override updateResizeActive(active: boolean): void {
     super.updateResizeActive(active);